Thermal cut-out.



G. D. HASKINS.

THERMAL CUT-OUT.

AYPLIGATION FILED SEPT. 19. 1904.

1,060,75?., Patented May 6, 1913.

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Witnesses I 4 1" ,1 Inventbr:

Caryl D. Haskins, by

UNITED STATES. PATENT OFFICE.

CABYL D. HASKINS, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRICCOMPANY, A. CORPORATION OF NEW YORK.

THERMAL CUT-OUT.

Specification of Letters Patent.

Patented May6,19i3.

Application filed September 19, 1904. Serial No. 224,998.

citizen of the United States, residing at Schenectady, county ofSchenectady, State of New .York, have invented certain new and usefulImprovements-in Thermal Cut-Outs, of which the following is aspecification.

The present invention relates to protective devices for electriccircuits and apparatus; and more particularly to that class of suchdevices commonly known as thermal cutouts or fuses.

As thermal cut-outs or fuses have been constructed heretofore 'they haveusually consisted of one or more wires or strips of metal which upon thepassage therethrough of an abnormal current suddenly become melted andvolatilized accompanied by loud dt-onations, the scattering of masses.of molten metal and the formation of dangerous electric arcs. Attemptshave been made to overcome these objections to this type of protectivedevice by inclosing-th'e wires or strips in a casing and surroundingthem by some substance which tends to' absorb or condense the gases ofvolatilization, but these attempts have been unsuccessful except in thesmallest sizes of fuses, but when, the fuse is required to-carrycurrents of considerable volume the mass of metal is so large andconcentrated that when an overload or short circuit takes place a verygreatvolume of gas is evolved with an explosive effect which is onlyslightly modified by the absorbent. material and casing, the latterbeing usually blown apart and the contents scattered.

The object'of my invention is to provide a thermal cut-out or fuse and amethod of constructing the same which upon the .occurrence of anoverload or short circuit will operate effectively, positively andwithout noise or explosive effect to interrupt the circuit.

In carrying out my invention I employ as the fusible member a wide andvery thin sheet or-layer of metal inclosed on both sides by a sheet orsheets of suitable insulation and, referably for the sake ofcompactness, roll t em 11 t gether in the form of a cylinder or tube.The metallic sheet may be made longerthan the insulating sheet sothatwhen rolled up there will be projectin ends of the metallic sheet towhich circult connections may be attached. but when it is desired tohave end sections ofbetter conductivity I make the sheet of insulatingmaterial longer than the metallic sheet and provide shortstrips of equalwidth of sheet metal of increased thickness and arrange them to overlapshort sections of the metallic sheet at its end edges and to projectbeyond the outer edges of the sheet insulation and connect theprojecting ends of theseterminal sheets in a suitable. manne to circuitterminals. lVhen an overload or short circuit traverses a fuse thusconstructed a minimum amount of metal is displaced andvolatilized, theare which forms between the adjacent edges of the undisplaced portions'of the fuse is widely distributed and subdivided into a multitude ofmultiple sinall arcs, and all of the displaced metal is volatilized sothat no masses of molten metal are formed.

In order to protect my fuse from mechanical injury, I inclosc it in acasing comprising a barrel of stoutinsulating fiber and removablemetallic end ieces which connect on their inner sides with the ends ofthe fuse and have provision on their outer sides for engagement with theordinary line terminal. 'Whena fuse has blown it may be readily replacedby a perfect fuse by removing the end pieces.

For a more complete understanding of in invention reference may be hadto the fo lowing detailed description and the accomanyin drawing forminga .part of this l7 specification, in which Figure 1 is a view inperspective of a partially rolled-fuse embodying one form of myinvention; Fig. 2 is a. greatly magnified longitudinal section of a partof the fusible member, the insulating sheet and the terminal strip; Fig.3 is a-view in part side elevation and part section of a casing with thecomplete fuse therein; and Fig. 4 is a cross section on line 4-4 of'Fig. 3, showing the means for protecting the ends ofthe fuse frominjury in connecting and disconnecting the end pieces of the casing.

The construction of a fuse according to my invention from silvered ormetallic coated paper is disclosed and specifically claimed in. aseparate application, and accordingly I will confine thisdescriptiontothe construction of my improved fuse in which the fusible member is inthe form of an independent sheet of metal.

As shown in Figs. 1 and 2, the fusible element consists of a sheet 1 ofmetal having a length depending uponthe potential of the current to becarried, a width proportional to the volume of the current and athickness of a thousandth of an inch or thereabout;-

gold leaf. silver leaf, tin foil and lead' foil being well adapted forthis purpose, butit is to be'understood that any metal or alloy whichcan be economically beaten or rolled into thin sheets may be used. Inorder to render the fusible men'iberless conductive at a plurality ofpoints in its width, I cut a series of short slits 2 along its center.

The insulating sheet 3 consists of asbestos or other heat resistingpaper of substantially the same width as the fusible strip and somewhatlonger, so that when the latter strip is placed centrally thereon aconsiderable length of the paper will project beyond the end edges ofthe metal as shown at 4 4. After the fusible strip 1 has been placedupon the paper strip a. short length 5 of thicker-sheet metal, such asheavy tin foil, is placed to overlap each of the end edges of'thefusible strip 1 and project a considerable distance beyond the end edgesof the paper strip to form terminals 6 for the fusible member and thenthe four strips are rolled up tragsversely as a single sheet and theouter side of the paper pasted down upon the back of its outerconvolution.

The projecting terminals 6 are compacted by pressure and connected bysoldering or otherwise to solid metallic end pieces 7. In the presentinstance the end pieces '4' are made with bell-shaped ends 8 for therecep tion of-the foil terminals 6, the shanks 9 are 'made rectangularand the outer ends 10 screw threaded. The casing consists of a tube 11of fibrous insulation having a bore large enough to receive the fusewith slight clearance, and provided at each.. -'end; with external screwthreads and internal longitudinal grooves 12 diametrically arranged, andmetallic caps 13 each provided with two internally screw-threaded ringflanges l-l and 15 to receive the end of the tube and an end piece 7,and on the side opposite the flanges with contact blades 16 forengagement with the ordinary terminal clips of the circuit.

In order to prevent the .foil terminals 6 from being twisted orotherwise injured by screwing or unscrewing. the caps 13, I provide aholder 17 at each end consisting of a sheet iron stamping having apolygonal aperture through which the shank of the end piece 7 passes andcontracted ends which enter the grooves 12 in the inner walls of thetube.

If desired the space-beneath the caps may be filled with some absorbentpowder to condense any slight amount of volatile gas that may be blownout at the ends ofthe fuse roll upon the passage of a heavy shortcircuit.

.1 do not desire to restrict myself to the particular form orconstruction of parts herein described and shown, since it is' a parentthat they may be changed and motii fied without departing from myinvention. What I claim as new and desire to secure by Letters Patent ofthe United States, i's,--

'1. A thermal cut-out comprising a wide sheet of thin leaf like metalwhich upon blowing produces a wide distribution of the are, and terminalstrips of thicker metal jpined ,to the opposite ends of said metal sieet.

A thermal cut-out comprising a wide sheet of thin leaf like sheet metalinclosed by sheet insulation of greater length, and terminal strips ofthicker metal joined to the opposite ends of said metal sheet andprojecting beyond the ends of said sheet iii-- sulation.

3. A thermal cut-out comprising a sheet of'thin metal rolled uptransversely with its convolutions out of contact with each other, andmeans at the ends of said roll of metal for connecting it in circuit.

. 4. A thermal cut-out comprising a sheet of thin metal rolled uptransversely with in- 4 sulation between the several convolutions andmeans at the ends of said roll of metal for connecting it in circuit.

A thermal cut-out comprising a sheet of thin metal. a sheet ofinsulation upon which said metal sheet is disposed, and two strips ofsheet metal of greater conductivity lapping the opposite ends of saidmetal sheet and extending beyond the ends of said insulating sheet; theseveral arts being rolled up transversely with St! 'cient compression tohold said strips in permanent contact with the ends of said metal sheet.

6. A thermal cut-out comprising a sheet of thin metal. a longer sheet ofinsulation I arranged to project beyond the ends of the metal sheet. andtwo thicker strips of metal joined to the OlJlJtbllt. ends of saidmetal' sheet and projecting beyond the ends of said insulating sheet andthe whole rolled up transversely.

T. The combination of a fuse member having metal end pieces ofnon-circular cross section. a tube surrounding said fuse memher andprovided with sup 'iorting bridge pie es having non-circular aperturesfor the reception of the ends of the fuse, and ren'iovahle end capsprovided with means for engaging the ends of the tube and the end piecesof the fuse ll'ltll'llJQl. 4

The combination of a fuse member ha ving strew-tln'eaded end pieces. aninsulating tube surrounding said fuse member and provided at it e1..lswith external -crcw threads and internal longitudinal grooves. bridgepieces located in said grooves and adapted amps? i g to engage said endpieces and prevent rotation thereof relative to the tube, and end capseach provided with screw threads adapted to engage the screw.threads ofan end piece of the fuse and an end of the tube.

9. A fuse strip composed of a band of metal disposed in a roll havingits convolut'ions' separated by insulating material, with means forconnecting the opposite ends of the roll to circuit terminals, wherebythe current flows in a longitudinal direction through the roll.

10. The combination in electrical fuses, of a fuse strip consisting of aband of metal disposed in a roll having insulating material between itsconvolutions, and conducting members secured to the opposite ends of theroll for connecting it to circuit terminals, whereby the current flowsin a longitudinal direction through the roll.

11. The combination in electrical fuses, of a fuse strip consisting of aband of metal disposed in a roll having insulating material between theconyolutions, conducting members secured to the opposite ends of theroll, and a casing iuclosing the fuse and connccted .to the said membersfor connection with circuit terminals.

12. A fuse strip consisting of a rolled band of metal having a reduced.area of cross section at a plane between the ends 01 the roll andtransverse to the longitudinal center of the roll.

13. A fuse strip consisting of 0. rolled band of metal, terminalssecured to the ends of the roll to carry the current longitudinally ofthe roll, the said roll having an area of cross section which is smallerat a point between the ends of the roll thanat the said ends. I

14. In a fuse, a fuse strip consisting of it rolled band of metal,terminals connected at opposite ends of the roll to carry the currentlongitudinally of'the roll, the said band being provided withperforations for reducing its area of cross section at a portionapproximately midway of the length of the roll.

15. In a safety fuse, the combination of a rolled band of metal,terminals secured to the ends of the roll, insulating means for keepingthe convolutions of the roll from contact with each other, the said bandbeing perforated approximately midway of the length of the roll toreduce the area of cross section of the roll to predetermine thelocation of the rupture.

16. A fuse strip composed of a band of metal rolled upon itselfso as toleave spaces between the convolutions, and means for passing a currentin a longitudinal direction through the roll.

17. A fast: strip comprising a band of metal rolled upon itself andhaving ltSCQIlvolutions separated by insulating material,

and means for passing a current in a longitudinal direction through theroll.

18. The combination in electrical fuses,

of a fuse strip consisting of a spirally rolled 20. The combination inelectrical fuses,

of a fuse strip-consisting of a bentband of metal having insulatingmaterial between the bends, a casing surrounding the fuse strip andhaving end closures of conducting material, and conducting means forconnecting the end closures with the opposite edges of the strip.

21. A fuse comprising a bent band of metal, terminals connected to theoutside bent edges of the band to carry the current longitudinally ofthe bend, and insulating material surrounding the band and separatingthe bent plies thereof.

22. A fuse comprising a bent band of metal, terminals connected to theopposite bent edges of the band, a casing for the band and-itsterminals, insulating material sur, rounding the band and separating the'plieS thereof, and finely divided insulating material filling the spacewithin the casing not occupied by the other parts contained therein.

23. A cut-out for electric circuits, comprising a sheet of thin metaldisposed in superposed layers separated byinsulating material, and meansat the ends of said layers for connecting the sheet in circuit.

24.- A fuse strip consisting of a sheet of thin. metal disposed insuperposed layers separated by insulating material and having a reducedarea of cross-section between the bent opposite edges of the-layers. v

25. In .an electric fuse, the combination of superposed layers of' sheetinsulation, a

sheet, metal fusible member interposed between said layers andprojecting beyond the ends thereof, and metallicconnectlons soldered tothe projecting endsof said fusible member.

26. In an electric fuse, the combination of a roll of sheet insulation,a sheet of fusible .metal extending therethrough and'projecting beyondthe ends of sa-id roll, and metallic connections soldered to the proectmg ,ends' of the metal sheet,

27. In an electric fuse, the combination of a roll of sheet insulation,a sheet of fusible metal interposed between the convolutions of saidinsulation and projecting beyond the ends thereof, and metal connectionssoldered to the projecting ends of said metal sheet.

In an electric fuse, the combination of a roll of sheet insulation, asheet of fusible metal interposed between the convolutions and the saidband soldered to the opposite ends of'the strip.

30. In a fuse, a fuse strip consisting of a rolled hand of metal,terminals fused to opposite ends of the roll to'carrythe currentlongitudinally of the roll, the said band being provided withperforations for' reducmg its area of cross section at a portionapproximately midway of the length of the roll.

31. In a fuse,- a fuse strip consisting of a rolled band of metal,terminals fused to opposite ends of the roll to carry the current-Tongitudinally of the roll, the said band being provided withperforations for reduc ing its areaof cross section at'a portionapproximately'midway of the length of the roll, and insulating means forkeeping the eonvolutions of the'roll from contact. with each other. Inwitness whereof I have hereunto set my hand this 15th day of September,1904.

' CARYL D. HASKINS. lVitnesses: v

BENJAMIN B. HULL, HELEN ORFORD.

